Electric-arc mechanism for searchlights



L. C. JUSEPHS, JR. ELECTRIC ARC MECHANISM FOR SEARCHLIGHTS.

APPLICATION FILED JUNE 9. 1939.

1,423,497, Patented July 18, 1922.

L. C. JOSEPHS, JR. ELECTRIC ARC MECHANISM FOR SEARCHLIGHTS.

APPLICATION FILED JUNE 9,1919.

Patented J uly 18, 1922.

3 SHEETS SHEET 2.

L. C. JUSEPHS, JR. ELECTRIC ARC MECHANISM FOR SEARCHLIGHTS.

APPLICA ION FILED JUNE 9.1919.

Z w 2 W B h hm J P0 Iv d3 2 W n 1% a P UNITED STATES PATENT OFFICE.

LYMAN C. JOSEPHS, JTL, OF THE UNITED STATES ARMY, ASSIGNOR TO ,NEWTON D.

I BAKER, SECRETARY OF WAR, TRUSTEE.

ELECTRIC-ARC MECHANISM FOR SEARCHLIG'HTS.

Specification of Letters Patent.

Patented July 18, 1922.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. In, 625.)

ment in Electric-Arc Mechanism for Search lights, of which the followingis a specification. 7

The invention described herein may be used by the Government, or any ofits officers or. employees in prosecution of work for the Government orby any other person in the United States without payment of any royaltythereon.

My invention relates to electric arc mechanisms for light projectors orsearchlights and has for its object to provide a simple and reliable arcmechanism and means for operating same.

Further objects of my invention are to provide means for automaticallycontrolling the burning of the arc' and for readily dissipating the heatgenerated by it.

In my co-pending application, Serial No. 301,569, filed June 7, 1919,there is shown and described a portable field Searchlight of the opentype, in which the arc mechanism is carried in an enclosing casing thatis sup:

ported and operated from the front of the mirror. The are mechanismshown therein, while extremely simple, is not well adapted for properlycontrolling the burning of a high intensity arc.

According to the present invention, I provide an improved form of arcmechanism that is particularly well adapted for burn ing a highintensity are and means for controlling the operation of the same, thatis advantageously arranged for the convenience of the operator.

I further provide means for electromagnetically controlling the flame ofa high intensit arc and for dissipating the heat generated by it.

In the accompanying drawings:

Fig. 1 is a three-quarters view in per-.

ing from opposite ends of the arc casing.

Fig- 5 is a transverse sectional view of thearc casing and mechanism.

Fig. 6 is an enlarged detailed view of the negative carbon holder alongthe line 5-5 of Fig. 5.

Fig. 7 is a detailed sectional view of the rotating mechanism for thepositive carbon.

Fig. 8 is a similar view of the negative carbon holder on the line 88.of Fig. 6.

Fig. 9 is a fragmentary detail of the positive carbon feeding mechanism.

Fig. 10 is a similar view of the motor construction associated with thefeeding mechamsm.

Fig. 11 is a sectionized detail of the motor construction shown in Fig.10.

Fig. 12 is a detail of the negative electrode feeding mechanism.

- Referring to Figs. 1 and 2, the carriage generally comprises arectangular frame 1 supported by axles 2 that are provided with wheels3. A turntable 4 is rotatably carried upon the frame 1 by rollers 5 andis provided with upward extending trunnion. arms 6. It is to beunderstood that the turntable and carriage may be of any suitable form,as they form no part of the present invention.

A mirror frame 7 is pivotally mounted between the trunnion arms 6 bymeans of trunnions 8. A mirror 9 is carried within the frame 7. A hollowcylindrical casing 10, which contains the arc mechanism, is centrallysupported in front of the mirror 9 by a plurality of arms 11 that aresecured to the rim of the mirror frame 7.

Referring now to Fig. 5, the arc mechanism comprises a positivecarbonhead 12 centrally supported within the casing 10 by means ofradial arms 12* secured to. the easing 10. A cupshaped shield 13surrounds the head 12 and 'is secured thereto by means of bolts 14. Theshield 13 is insulated from the head 12 by insulating washers 15 and 16.The shield 13 is preferably composed of copper, or any other metal thateasily conducts heat and is made of ample cross section, so that aconsiderable mass of metal of high heat conductivity and having a largeradiatin surface, surrounds the positive head 12. he shield 13 isprovided with a slot 17 the purpose of which will be hereinafterdescribed. A tip or bushing 18, also formed of a metal having a highheat con ductivity, such as copper, extends through a central opening 19in the shield 13 and is clamped against the insulating washer 15 bymeans of the shield 13 and the insulating washer 16, which is providedwith a flange opening 20. v

A positive carbon 21 extends through the head 12 and the bushing 18 andprojects beyond the end thereof. Current is conducted to the carbon 21by means of brushes 22, which are located in slots 23 provided in thehead 12 and flexible leads 24 that are connected to a cable 25 whichextends through the casing 10. The carbon 21 is adapted to be movedlongitudinally b means of a roller 26 that engages the si e of thecarbon 21 and is mounted on a shaft 27. The shaft 27 is rotatablysupported by means of a bracket 28 that is secured tothe arms 12*. Asbest shown in Figs. 1 and 3, the shaft 27 is connected to a second shaft29, which extends to a point outside the easing 10 by means of aninsulating coupling 30. An operating shaft 31 is mounted at one end in abracket 32 secured to the rim of the mirror frame 7 and is connected atits other end to the shaft 29 by means of a universal joint 33. Theshaft 31 is provided with an operating handle 34 by ,means of whichmovement of the positive carbon 21 may be obtained through the shafts27, 29 and 31.

The positive carbon 21 is adapted, to be given a turning movement bymeans-of a wrench device, best shown in Figs. 5 and 7. A lever 35 isprovided with a bifurcated portion between the arms of which a secondlever 36 is loosely pivoted'at the point 36. The lever 35 is adapted tobe given a reciprocating motion by means of a rod 37 that is connectedby an insulating coupling 39 to a rod 38 that extends through the casing10. The rod 38 is connected at its end to a crank disc 39, as'best shownin Figs. 10 and 11. The disc 39 is driven by a worm wheel 40 that is inmesh with a worm 41 mounted on the shaft 42 of an electric motor 43. Themotor 43 is supported from the rim of the mirror frame 7 by means of abracket 44. The reciprocating motion of the rod 37 causes the levers 35and 36 to alternately engage and disengage the carbon 21, in a mannersimilar to the action of a Stillson wrench, thus imparting a step bystep turning movement to the carbon 21.

Referring again to Fig. 5, a ne ative carbon 50 is supported by a head51 that is carried at the end of a conductor-arm 52. The conductor arm52 asses through the shield 13, being insulate secured to one of thearms 12 by means of bolts 54 and insulating plates 55. Current isconducted to the arm 52 by means of a therefrom at 53,- and is flexibleconductor 56=from whence it passes along the arm 52 and then upwardly tothe head 51. The head 51 is disposed at an an agle to the axis of thepositive carbon 21, so that the flame from the negative carbon 50impinges upon the positive carbon 21 in such a manner as to tend to keepthe positive flame within the crater formed at the end of the positivecarbon.

It is well known that in order to maintain a good crater when burninghigh intensity carbons, the negative flame should impinge against theend of the positive carbon at such an angle that the resultant flame ofthe two carbons sweeps away from the crater. However, the tendencyalways exists for the flame to waver, due to irre lar burning orcurrents of air, which resu ts in the formation of a poor crater withconsequent loss of light.

The burning of a high intensity are with a mechanism arranged as shownin Fig. 5, is stabilized by the magnetic field surrounding the conductorarm 52, which tends to direct the flame away from the field. Thistendency of the arc flame is further increased by the fact that the slot17 in the shield 13 is located opposite the conductor arm 52, so thatthe heated products of combustion from the arc naturally pass throughthe slot 17, rather than around the edges of the shield .13. Thecombined influence of magnetic field and a ventilating passageoppositely disposed with respect to the arc, results in a Very steadyburning of the are, so all that is necessary to maintain a proper crateris to rotate the positive carbon 21.

The negative carbon is adapted to be moved longitudinally by means ofrollers 57, which are located in openings 58 rovided in the negativehead 51. The roilers 57 arepivotally mounted in brackets 59 and areadapted to be held in engagement with the sides of the carbon 50 bymeans of levers 61. The levers 61 are ivotally mounted on the head 51 at62 and are held in engagement with the brackets 59 by means of springs63, which are secured to rin 6t that surrounds the carbon 50. One 0 therollers 57 is mounted on a shaft 65 that is connected through aninsulating coupling 66 to a second shaft 67 that extends outside thecasing 10. An operating'rdd 68 is carried at one end by a bracket 69supported from the rim of the mirror frame 7 and is secured at the otherend to the rod 67 through a universal joint 70. The rod 68 is providedwith a handle 71 by means of which'the rollers 57 may be turned throughthe shafts 68, 67 and 65.

From the foregoing, it is apparent that an arc mechanism constructed inaccordance with my invention is exceedingly simple and that itsoperation may readily be controlled from the rear of the mirror frame. Furnetic field and natural draft and the heat from the arc is readily'dissipated by the presence of a mass of metal of high heat conductivityand large radiating surface surrounding the positive carbon.

While I have shown my invention in its simplest form, it is obvious thatfurther imrovements and changes may be made therein within ,the scope ofthe appendedclaims.

I claim as my invention:

1. In a high-intensity arc mechanism, the combination with positive andnegative carbons, a shield surrounding the positive carbon and providedwith an openin and a housing for the shield, of means orelectroinagnetically directing the arc flame into said opening.

2. An electricarc mechanism, comprising a shield, providing a radiatingsurface and having a ventilatin opening, a casing surrounding the shied, a positive electrode slidable through said shield, a negativeelectrode cooperating with the positive electrode to produce an arcflame, and means for establishing an electromagnetic field in thevicinityof the arc flame to direct the latter toward the ventilatingopening.

3. An electric arc mechanism, comprising a shield providing an extensiveradiating surface of high heat conductivity and having a ventilatingopening, a casing surrounding the shield, a positive electrode slidablethrough said shield, a negative electrode co-operating with the positiveelectrode to produce an arc flame and means for establishing anelectromognetic field in the vicinit of the arc flame to direct thelatter towar said ventilating opening.

4. An electric arc mechanism comprising a radially slotted shieldproviding a radiating surface of high heat conductivity, a casingsurrounding the shield, at positive electrode slidable through thecentral portion of said shield, a negative electrode 00- operating withthe positive to produce an arc flame, and means for establishing anelectromagnetic field in the vicinity of the arc flame to direct thelatter toward the slot in said shield.

5. An electric arc mechanism com rising a shield radially slotted abovethe p ane of its horizontal axis and providin a radiating surface ofhigh heat conduct1vi ty, a casing surrounding theshield, a positiveelectrode slidable through said shield,.a negative electrodeco-operating with the posi tive electrode to produce-an arc flame andmeans for electromagnetioally controlling the arc flame and directingthe latter toward the slot in said shield.

6. In a high intensity are mechanism the combination with positive andnegative electrodes, a slotted shield surrounding the positive electrodeand a housing inclosing the shield; of means for directing the are flameI through the slot of said shield.

LYMAN o. JOSEPHS, JR.

